Raet1e, also known as retinoic acid early-inducible protein 1-epsilon, is a member of a family of cell-surface proteins that function as ligands for mouse NKG2D. All Rae-1 family members bind to mouse NKG2D, an activating receptor expressed on NK cells and some T cell subsets, resulting in the activation of cytolytic activity and cytokine production by these effector cells. Recombinant mouse Raet1e, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.